1. Field of the Invention
This invention relates to a new photoconductive polymer material.
2. Discussion of the Prior Art
A vast variety of high-molecular weight compounds have been reported to have photoconductive properties. Such compounds include, for example, a resinous material resulting from the condensation of a saturated aliphatic aldehyde with a primary aromatic amine as described in U.S. Pat. No. 3,244,517, a resinous material manufactured by the condensation of an aromatic amine containing a conjugated heterocyclic nucleus with an unsaturated aldehyde, acrolein or an alkyl-substituted acrolein as described in U.S. Pat. No. 3,163,531, a relatively low molecular weight polycondensation product of formaldehyde or para-formaldehyde and anthracene or an N-alkylcarbazole, as set forth in U.S. Pat. No. 3,240,597, a product resulting from the condensation of N-.beta.-chloroethylcarbazole with formaldehyde or para-formaldehyde as set forth in U.S. Pat. No. 3,770,428, poly-N-vinylcarbazole as set forth in U.S. Pat. No. 3,037,861, etc.
Among these, only poly-N-vinylcarbazole has been applied to commercial products because it exhibits a relatively high level of photoconductivity and is readily synthesized with comparatively low production cost. Even this compound has many shortcomings including still insufficient photoconductivity and in particular too high a softening point. The latter property leads to a coated film with an unacceptable fragilness.
U.S. Pat. No. 3,240,597 and Japanese Patent Publication 5585/1967 (corresponding to British Pat. No. 1,021,994) disclose an organic photoconductive composition based on a resinous material prepared by condensing an N-alkylcarbazole such as N-ethylcarbazole with formaldehyde; however, such an N-alkylcarbazole-formaldehyde resin exhibits very limited solubilities in common organic solvents, and has too high a softening point to give rise to a coated film with good mechanical strength. Such deficiencies are reflected in the fact that an image obtained by photo-electrophoresis (see, for example, Japanese Patent Publication 21781/1968, U.S. Pat. Nos. 3,383,993, 3,384,488, 3,384,565, 3,384,566, 3,510,419, 3,565,614, 3,615,558, 3,655,370 and 3,681,064, and British Pat. Nos. 1,124,625, 1,124,626 and 1,185,931), photo migration process (see, for example, U.S. Pat. No. 3,520,681), or manifold process (see, for example, Japanese Patent Publication 8118/1972, corresponding to British Pat. No. 1,214,731) using a finely divided photoconductive particulate comprising one of these photoconductive resinous materials must be fixed only at a very high temperature exceeding its softening point, giving a fixed image with an insufficient mechanical strength.